EP2060938A1 - Fibre optique et matériau à base de fibre optique - Google Patents

Fibre optique et matériau à base de fibre optique Download PDF

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Publication number
EP2060938A1
EP2060938A1 EP07807237A EP07807237A EP2060938A1 EP 2060938 A1 EP2060938 A1 EP 2060938A1 EP 07807237 A EP07807237 A EP 07807237A EP 07807237 A EP07807237 A EP 07807237A EP 2060938 A1 EP2060938 A1 EP 2060938A1
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Prior art keywords
core
refractive index
radius
optical fiber
wavelength
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German (de)
English (en)
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EP2060938A4 (fr
Inventor
Takeshi Yoshida
Tomohiro Nunome
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Fujikura Ltd
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Fujikura Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • G02B6/03644—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - + -
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03605—Highest refractive index not on central axis
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03605—Highest refractive index not on central axis
    • G02B6/03611—Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
    • G02B6/0286—Combination of graded index in the central core segment and a graded index layer external to the central core segment

Definitions

  • the present invention relates to an optical fiber and an optical fiber preform.
  • SBS stimulated Brillouin scattering
  • SBS threshold power a predetermined intensity of light
  • FTTH fiber to the home
  • Patent Document 1 As a technique for suppressing SBS, as described above, the technique for changing a dopant concentration or a residual stress in a longitudinal direction is reported (Patent Document 1). However, in this technique, optical characteristics are changed in the longitudinal, so that this technique is not preferable for practical use.
  • Patent Documents 2 to 5 and 7 techniques for suppressing SBS by giving a refractive index profile for an optical fiber. In theses techniques, a change in optical characteristics in a longitudinal direction does not occur. However, a structure having a refractive index profile suitable for desired characteristics is needed.
  • Patent Documents 2, 3, and 5 for an optical fiber described which has a three-layer structured refractive index profile, the refractive index profile is set to a suitable condition, thereby suppressing SBS and obtaining the same optical characteristics as ITU-T Recommendation G.652 (hereinafter, referred to as G652).
  • G652 ITU-T Recommendation G.652
  • not all structures described in Patent Documents 2, 3, and 5 satisfy the same optical characteristics as G652, and when manufacturing is practically performed on the basis of these conditions, a suitable design value for each condition is needed.
  • Patent Document 4 a uniform bending loss becomes worse, and in consideration of handling of the optical fiber, this phenomenon is not preferable.
  • fluorine needs to be added at an intentional position, so that manufacturing a preform using a VAD method is difficult.
  • Patent Document 7 only the shape of a refractive index profile is described, and detailed parameters and the like are not mentioned.
  • An object of the invention is to provide an optical fiber and an optical fiber preform which have stable characteristics in a longitudinal direction, compatibility with G652, excellent manufacturability, and suppressed SBS, by giving a structure design value for a suitable refractive index profile.
  • an optical fiber having a refractive index profile constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a substantially uniform positive relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a substantially uniform positive relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a substantially uniform positive relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, wherein ⁇ 2 is equal to or less than 0.4%, ⁇ 1, ⁇ 2, and ⁇ 3 have relationships of
  • an optical fiber having a refractive index profile constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a maximum relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a minimum relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a maximum relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, wherein ⁇ 2 is equal to or less than 0.4%, ⁇ 1, ⁇ 2, and ⁇ 3 have relationships of ⁇ 1> ⁇ 2,
  • an optical fiber preform having a refractive index profile constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a substantially uniform positive relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a substantially uniform positive relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a substantially uniform positive relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, wherein ⁇ 2 is equal to or less than 0.4%, the ⁇ 1, ⁇ 2, and ⁇ 3
  • an optical fiber preform having a refractive index profile constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a maximum relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a minimum relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a maximum relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, wherein ⁇ 2 is equal to or less than 0.4%, ⁇ 1, ⁇ 2, and ⁇ 3 have relationships of ⁇ 1>
  • An optical fiber of the invention has a refractive index profile constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a substantially uniform positive relative refractive index difference ⁇ 1in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a substantially uniform positive relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a substantially uniform positive relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, or has a refractive index profile constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having
  • ⁇ 2 is equal to or less than 0.4%
  • X and Y satisfy 0.25% ⁇ X ⁇ 0.6%, 0.1% ⁇ Y ⁇ 0.6%, and a relationship of (2*X-0.7)% ⁇ Y ⁇ (X/2+0.4)%
  • ⁇ 2, ⁇ 3, R1, and R2 satisfy relationships of ( ⁇ 2+ ⁇ 3)+1.0 ⁇ R2/R1 ⁇ 7*( ⁇ 2+ ⁇ 3)-1.45 and ⁇ 2+ ⁇ 3 ⁇ 1.15
  • a cable cutoff wavelength is less than 1260 nm
  • a mode field diameter is in the range of 7.9 to 10.2 ⁇ m at a wavelength of 1.31 ⁇ m
  • a zero-dispersion wavelength is in the range of 1300 to 1324 nm
  • the optical fiber of the invention may be manufactured by drawing a preform manufactured by a typical VAD method.
  • the manufacturing method of the preform is not limited to the VAD method, and well-known OVD and CVD methods can be used.
  • FIG. 1 is a graph showing occurrences of SBS in an optical fiber.
  • SBS threshold a threshold of an occurrence of SBS.
  • FIG. 2 is a view illustrating a configuration of an SBS threshold measurement system.
  • reference numeral 1 denotes a light source at a wavelength of 1.32 ⁇ m
  • reference numeral 2 denotes a light source at a wavelength of 1.55 ⁇ m
  • reference numeral 3 denotes an EDFA
  • reference numeral 4 denotes a power meter for measuring backscattered light power
  • reference numeral 5 denotes a 9:1 1 coupler
  • reference numeral 6 denotes a power meter for measuring incoming light power
  • reference numeral 7 denotes a power meter for measuring transmitted light power
  • a reference numeral 8 denotes an optical fiber to be measured.
  • the three power meters 4, 6, and 7 are connected through the 9:1 coupler 5 to measure the power of incoming light, backscattered light, and transmitted light of the optical fiber 8 to be measured.
  • incoming light power at the maximum second-order differential equation of the backscattered light with respect to the incoming light becomes an SBS threshold.
  • an SBS threshold is evaluated by using the same measurement system and definition.
  • the definition of the SBS threshold is considered as definition 4 in the following document. Shimizu, "A Study on Definition of the SBS Threshold in a Single-Mode Optical Fiber", Institute of Electronics, Information and Communication Engineers, General Conference in 2005, B-10-66.
  • the SBS threshold is dependent on a mode field diameter (hereinafter, referred to as MFD).
  • MFD mode field diameter
  • a plot result obtained by calculating the MFD dependence of the SBS threshold of a single-mode optical fiber (hereinafter, referred to as SMF) which has a typical refractive index profile of step-index model as shown in FIG. 4 and satisfies the G652 standard is shown in FIG. 3 .
  • SMF single-mode optical fiber
  • the SBS threshold of the SMF changes in the range of 7.4 to 9.7 dBm. Accordingly, when the SBS threshold is compared, an optical fiber having the same MFD needs to be compared.
  • the optical fiber of the invention has optical characteristics described in G652 in that a cable cutoff wavelength is less than 1260 nm, an MFD at a wavelength of 1.31 ⁇ m is in the range of 7.9 to 10.2 ⁇ m, a zero-dispersion wavelength is in the range of 1300 to 1324 nm, a zero-dispersion slope is equal to or less than 0.093 ps/(nm 2 ⁇ km), a uniform bending loss is equal to or less than 2 dB/m at a bending diameter of 20 mm and a wavelength of 1.31 ⁇ m, and an SBS threshold is equal to or higher than two times (+3 dB) that of an SMF having the same MFD.
  • FIG. 5 is a view illustrating a first example of a refractive index profile of the optical fiber of the invention.
  • the refractive index profile is constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a substantially uniform positive relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a substantially uniform positive relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a substantially uniform positive relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, wherein ⁇ 1> ⁇ 2 and ⁇ 3
  • FIG. 6 is a view illustrating a second example of a refractive index profile of the optical fiber of the invention.
  • the refractive index profile is constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a maximum relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a minimum relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a maximum relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core and has a substantially uniform refractive index, wherein ⁇ 1> ⁇ 2 and ⁇ 3> ⁇ 2.
  • optical fiber having the refractive index profile constituted by the three-layer structured core and the one-layer structured cladding for surrounding the core in order to obtain an optical fiber which has the above-mentioned optical characteristics, that is, characteristics compatible with G652 and an SBS threshold equal to or higher than two times that of (by +3 db) the SMF having the same MFD as the optical fiber of the invention, detailed examinations were repeated. As a result, it was found that relationships between ⁇ 1, ⁇ 2, ⁇ 3, R1, R2, and R3 were limited.
  • SBSeff is defined by the following expression.
  • SBSeff SBS threshold of the optical fiber of the invention-SBS threshold of the SMF having the same MFD as the optical fiber of the invention
  • ⁇ 2 be equal to or less than 0.4%.
  • the position of the third core in the radial direction represented as R2/R1 needs to be suitably determined depending on the sum of ⁇ 2 and ⁇ 3, that is, ⁇ 2+ ⁇ 3.
  • ( ⁇ 2+ ⁇ 3) and R2/R1 satisfy relationships of ( ⁇ 2+ ⁇ 3)+1.0 ⁇ R2/R1 ⁇ 7*( ⁇ 2+ ⁇ 3)-1.45 and ⁇ 2+ ⁇ 3 ⁇ 1.15.
  • the relationships between ( ⁇ 2+ ⁇ 3) and R2/R1 satisfying the condition are shown in FIG. 9 .
  • FIG. 10 is a view showing a relationship between ⁇ 3- ⁇ 1 and SBSeff.
  • SBSeff significantly changes with a slight change in relative refractive index difference.
  • ⁇ 3- ⁇ 1 is positive, the change rate of SBSeff with respect to the change in relative refractive index difference is small.
  • SBSeff is approximated to a quadratic equation of ⁇ 3- ⁇ 1, the approximation curve is a parabola which opens down, and the inflection point is ⁇ 3- ⁇ 1>0.
  • FIG. 11 is a view showing a relationship between ⁇ 1- ⁇ 2 and SBSeff. As shown in FIG. 10 , ⁇ 1 is 0.5%, ⁇ 2 is 0.22%, ⁇ 3 is in the range of 0.40 to 0.65% at an interval of 0.025%, and R2/R1 is 2.2.
  • Table 1 in other combinations of ⁇ 1, ⁇ 2, ⁇ 3, R1, R2, and R3, the inflection point is ⁇ 3- ⁇ 1>0, and it can be seen that SBS characteristics which are always stable can be obtained when ⁇ 3- ⁇ 1 is positive. It is preferable that ⁇ 1- ⁇ 2 be equal to or greater than 0.25%.
  • FIG. 11 is a view showing a relationship between ⁇ 1- ⁇ 2 and SBSeff. As shown in FIG.
  • ⁇ 1 is in the range of 0.44% to 0.56% at an interval of 0.03%
  • ⁇ 2 is 0.24%
  • ⁇ 3 is 0.55%
  • R2/R1 is 2.2.
  • FIG. 12 in a refractive index profile using other combinations of ⁇ 1, ⁇ 2, ⁇ 3, R1, R2, and R3, that is, when ⁇ 1 is in the range of 0.44% to 0.56%, ⁇ 2 is in the range of 0.18% to 0.26%, ⁇ 3 is in the range of 0.45% to 0.65%, and R2/R1 is in the range of 1.8 to 2.6, the same tendency can be obtained.
  • optical fiber of Example 1 which has the refractive index profile of FIG. 5 are shown.
  • structural parameters and optical characteristics of an optical fiber of Comparative Example 1 are shown.
  • the optical fiber of Comparative Example 1 is an SMF having a step-index profile as illustrated in FIG. 4 .
  • the optical fiber having the structural parameters of Example 1 related to the invention had an SBS threshold of 12.2 dBm for a length of 20 km, and could obtain a higher suppression effect than the optical fiber of Comparative Example 1 which had the same MFD by +3.5 dB.
  • the optical fiber of Example 1 had the same optical characteristics as the SMF of Comparative Example 1 and satisfied the G652 standard.
  • Table 3 shows results in the case where structural parameters of Example 1 are represented by using X, Y, and R2/R1 described above.
  • optical fibers having the structural parameters of Examples 1a to 1g shown in Table 3 had SBS thresholds of 12.4 to 13.3 dBm for a length of 20 km as shown in FIG. 13 and could obtain suppression effects higher than the SMF having the same MFD by +3.7 to +4.6 dB.
  • the optical characteristics of the optical fibers of Examples 1a to 1g all satisfied the G652 standard.
  • Tables 4 and 5 show results in the case where structural parameters of Example 1 are represented by using X, Y, and R2/R1 described above.
  • the optical fibers having the structural parameters of Examples 1a to 1g shown in Table 3 and Examples 1h to 1v shown in Tables 4 and 5 had SBS thresholds of 10.9 to 13.8 dBm for a length of 20 km as shown in FIG 14 and could obtain suppression effects higher than the SMF having the same MIND by +3.1 to +4.5 dB.
  • the optical characteristics of the optical fibers of Examples 1h to 1v all satisfied the G652 standard.
  • Example 1h Example 1i
  • Example 1j Example 1k
  • Example 11 Example 1m
  • Example 1n Example 1n
  • R3 ⁇ m 4.71 4.90 8.95 4.67 8.13 4.60 8.54 R2/R1 - 1.6 1.9 1.9 2.5 1.9 3.1 3.9 ⁇ 1 % 0.50 0.50 0.50 0.50 0.40 0.50 0.60 ⁇ 2 % 0.10 0.10 0.20 0.10 0.20 0.20 ⁇ 3 % 0.40 0.40 0.40 0.50 0.50 0.50 0.60 ⁇ 1- ⁇ 2 % 0.40 0.40 0.30 0.40 0.20 0.30 0.40 ⁇ 3- ⁇ 2 % 0.30 0.30 0.20 0.40 0.30 0.40 ⁇ 3+ ⁇ 2 % 0.50 0.50 0.60 0.60 0.70 0.70 0.80 Fiber cutoff wavelength ⁇ m 1.32 1.32 1.32 1.32 1.32 1.32 Cable cutoff wavelength ⁇ m
  • Table 6 shows optical characteristics in the case where structural parameters of a refractive index profile of the optical fiber having the refractive index profile of FIG. 6 are represented by using X, Y, and R2/R1 described above.
  • optical fibers having the structural parameters of Examples 2a to 2f shown in Table 6 had SBS thresholds of 12.0 to 13.7 dBm for a length of 20 km as shown in FIG. 15 and could obtain suppression effects higher than the SMF having the same MFD by +3.3 to +5.0 dB.
  • the optical characteristics of the optical fibers of Examples 2a to 2f all satisfied the G652 standard.
  • the amount of dopant GeO 2 in the core can be reduced, so that it is possible to reduce a loss in the optical fiber.
  • Table 7 shows optical characteristics in the case where structural parameters of a refractive index profile of the optical fiber having the refractive index profile of FIG. 6 are represented by using X, Y, and R2/R1 described above.
  • the optical fibers having the structural parameters of Examples 2a to 2f shown in Table 6 and Examples 2g to 2m shown in Table 7 had SBS thresholds of 10.8 to 14.3 dBm for a length of 20 km as shown in FIG. 16 and could obtain suppression effects higher than the SMF having the same MIND by +3.2 to +4.7 dB.
  • the optical characteristics of the optical fibers of Examples 2g to 2m all satisfied the G652 standard.
  • FIG. 17 shows a refractive index profile of an optical fiber of Example 3 related to the invention.
  • the refractive index profile in Example 3, as shown in FIG. 17 is constituted by: a three-layer structured core which includes, in the central portion of the core, a first core in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m; and a cladding which surrounds and comes in contact with the three-layer structured core.
  • the relative refractive index difference ⁇ 1 of the first core is defined as ⁇ which becomes equivalently uniform in the region from the center of the core to the radius R1
  • the relative refractive index difference ⁇ 2 of the second core is defined as a relative refractive index difference that becomes a minimum value in the region between the radii R1 and R2 ⁇ m
  • the relative refractive index difference ⁇ 3 of the third core is defined as a relative refractive index difference that becomes a maximum value in the region between the radii R2 and R3 ⁇ m.
  • the optical fibers of Examples 3 and 4 had SBS thresholds of 12.2 to 12.7 dBm for a length of 20 km, and could obtain higher suppression effects than the SMF having the same MFD by +3.5 to +4.0 dB.
  • the optical fibers of Examples 3 and 4 all satisfied the G652 standard.
  • FIG. 18 is a refractive index profile of an optical fiber preform of Example 5.
  • the optical fiber preform in this example is constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a substantially uniform positive relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a substantially uniform positive relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a substantially uniform positive relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m.
  • the three-layer structured core is included.
  • Structural parameters of the optical fiber preform of Example 5 are represented in Tables 9 and 10 by using X, Y, and R2/R1 described above, and optical characteristics that were exhibited when the preform was drawn into an optical fiber are shown.
  • the optical fiber drawn from the optical fiber preform of Example 5 had an SBS threshold of 10.9 to 13.8 dBm for a length of 20 km as shown in FIG. 19 , and obtained a suppression effect higher than the SMF having the same MFD by +3.1 to +4.5 dB, so that the G652 standard was further satisfied.
  • Example 5a Example 5b
  • Example 5c Example 5d
  • Example 5e Example 5f
  • Example 5g R1 ⁇ m 1.32 1.81 1.69 3.14 1.33 2.80 1.12
  • R2/R1 - 2.1 1.6 1.9 1.9 2.5 1.9 3.1 ⁇ 1 % 0.50 0.50 0.50 0.50 0.50 0.50 0.40 0.50 ⁇ 2 % 0.20 0.10 0.10 0.20 0.10 0.20 0.20 ⁇ 3 % 0.60 0.40 0.40 0.40 0.50 0.50 0.50 ⁇ 1- ⁇ 2 % 0.30 0.40 0.40 0.40 0.20 0.30 ⁇ 3- ⁇ 2 % 0.40 0.30 0.30 0.20 0.40 0.30 0.30 ⁇ 3+ ⁇ 2 % 0.80 0.50 0.50 0.60 0.60 0.70 0.70 Fiber cutoff wavelength ⁇ m 1.32 1.32 1.32 1.32 1.32 1.32 Cable cutoff wavelength
  • FIG. 20 shows a refractive index profile of an optical fiber preform of Example 6.
  • the optical fiber preform in this example is constituted by: a three-layer structured core which includes, in the central portion of the core, a first core having a maximum relative refractive index difference ⁇ 1 in a region from the center of the core to a radius of R1 ⁇ m, a second core which surrounds and comes in contact with the first core and has a minimum relative refractive index difference ⁇ 2 in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and has a maximum relative refractive index difference ⁇ 3 in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m.
  • the three-layer structured core is included.
  • Structural parameters of the optical fiber preform of Example 6 are represented in Tables 11 and 12 by using X, Y, and R2/R1 described above, and optical characteristics that were exhibited when the preform was drawn into an optical fiber are shown.
  • the optical fiber drawn from the optical fiber preform of Example 6 had an SBS threshold of 10.8 to 14.3 dBm for a length of 20 km as shown in FIG. 21 , and obtained a suppression effect higher than the SMF having the same MFD by +3.2 to +4.7 dB, so that the G652 standard was further satisfied.
  • Example 6a Example 6b
  • Example 6c Example 6d
  • Example 6e Example 6f
  • R2 ⁇ m 3.03 3.05 2.87 3.13 3.10 3.45
  • R3 ⁇ m 4.60 4.49 4.36 4.49 4.25 4.83
  • R2/R1 - 2.00 2.20 2.00 2.40 2.80
  • FIG. 22 shows a refractive index profile of an optical fiber preform of Example 7.
  • the optical fiber preform in this example is constituted by: a three-layer structured core which includes, a first core disposed in a region from the center of the core to a radius of R1, a second core which surrounds and comes in contact with the first core and is disposed in a region from the radius of R1 ⁇ m to a radius of R2 ⁇ m, and a third core which surrounds and comes in contact with the second core and is disposed in a region from the radius of R2 ⁇ m to a radius of R3 ⁇ m.
  • the three-layer structured core is included.
  • the refractive index profile smoothly changes, and the definition of the boundary thereof is the same as in Examples 3 and 4.
  • Structural parameters of the optical fiber preform of Example 7 are represented in Table 13, and optical characteristics that were exhibit when the preform was drawn into an optical fiber are shown.
  • the optical fiber drawn from the optical fiber preform of Example 7 had an SBS threshold of 12.6 dBm for a length of 20 km and obtained a suppression effect higher than the SMF having the same MFD by +3.8 dB, and the G652 standard was satisfied.
  • the relationships between the relative refractive index differences ⁇ 1, ⁇ 2, and ⁇ 3 of the layers are suitably designed, and the position of the third core is suitably determined. Therefore, it is possible to increase an SBS threshold by +3 dB or higher as compared with the SMF having the same MFD while maintaining the optical characteristics described in G652.
  • the relative refractive index difference of the third core is greater than that of the first core, it is possible to improve manufacturability of the optical fiber preform.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Optical Communication System (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)
EP07807237.8A 2006-09-14 2007-09-13 Fibre optique et materiau a base de fibre optique Withdrawn EP2060938A4 (fr)

Applications Claiming Priority (2)

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US20160034640A1 (en) 2014-07-30 2016-02-04 Sequenom, Inc. Methods and processes for non-invasive assessment of genetic variations
DE112015006766T5 (de) * 2015-08-04 2018-04-19 Sumitomo Electric Industries, Ltd. Optische Verbindungskomponente
CN108780189B (zh) * 2016-04-06 2021-11-19 特拉迪欧德公司 用于改变激光束轮廓的光纤结构和方法
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CA3050055C (fr) 2017-01-24 2023-09-19 Sequenom, Inc. Methodes et procedes d'evaluation de variations genetiques

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US7835609B2 (en) 2010-11-16
EP2060938A4 (fr) 2013-08-07
JP4677491B2 (ja) 2011-04-27
RU2401444C1 (ru) 2010-10-10
CN101535851A (zh) 2009-09-16
WO2008032779A1 (fr) 2008-03-20
CN101535851B (zh) 2011-01-26
US20090317040A1 (en) 2009-12-24

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